Manufacture of artificial silk



UNITED STATES PATENT OFFICE.

EKILE BBONNERT, OF IIILHAUSEN, ALSACE-LOBRAINE, FRANCE.

MANUFACTURE OF ARTIFICIAL SILK.

Io Drawing.

To all whom it may concern.

Be it known that I, EMILE BRONNERT, a citizen of the Republic of France, residing at 1 Quai du Barrage, in Miilhausen, Alsace- Lorraine, France, have invented certain new .and useful Improvements in the Manufaccreased according to the fineness of thread desired and the diameter of the nozzle opening selected to correspond.

In the applicants former patents it has been shown how success has been obtained in a practical manner in also obtaining the finest threads, of 1 denier for instance, from viscose by means of the apparatus usually employed for ordinary thicker threads of say 8 deniers, by which the threads do not fall to the bottom in the weak precipitant bath, but are drawn upward through astrong precipitant medium.

As is well known according to these proposals in general the concentration of the acid serving for decomposition had to be increased all the more the finer the threads that it was desired to produce.

Less essential in this connection was the guantity, used at the time, of the usual aditions to the acids or to the viscose itself it compatible with it, in order to tone down their all-too vigorous action'and in order to be able to leave the state of ripeness of the viscose out of consideration to a far reaching extent.

Now for reasons of convenience the technical viscose silk industry has, hitherto, as is well known substantially worked up grades of viscose which contained about 8% cellulose and about 7% caustic soda, although for special purposes not only other proportions between the said ingredients but also higher cellulose concentrations are in any case customary. I

In order to obtain the silk threads, hitherto solely produced upon a manufacturing scale in the technical world, of 6 deniers upward to about IOdeniers for each single thread, use was made of the nozzle apertures customary in'jconmction with nitro- Specification of Letters Patent.

Patented Oct. 11, 1921.

Application filed September 14, 1920. Serial No. 410,141.

cellulose and ammoniac copper silk of about 0.10 to 0.20 mm, diameter the viscose employed for the purpose, in order to avoid higher pressure being mostly such as can be obtained in any consistency desired for instance by using previously prepared cellulose or by suitable time and temperature measurement or by alteration of the stoichiometric proportions in the manufacture and graduation of the lowering of the molecular weight of the cellulose.

The more consistent the viscose to be worked up is selected, all the wider is it customary to select the nozzle apertures with a View to avoiding unnecessary highpressure.

Now it has been found that with viscose of different consistencies with varying thread titrations or counts the concentration of the acid must undoubtedly be relatively adapted to the known regulation conditions but, must however, be taken absolutely all the higher the greater the cross section which has been selected for the nozzle apertures in correlation to the greater consistenc of the corresponding viscose. The recognition of this fact is of the greatest importance for the technical man.

Example 1. A viscose of the usual composition is spun,

in the production of which however, the Y alkali cellulose has experienced in the known manner, a preliminary ripening of 3 days,

for instance at about 25 C. and which has been sulfidized at the ordinary temperature. After leavin the dissolving-apparatus the viscose is sub ected to a further several dayssubsequent ripening also at an ordinary temperaturc. It is then somewhat in the nature -of a thin liquid (about 100 viscosity units 2'. e. 100 seconds have been required to allow 100 com. of the corresponding viscose to flow out of the cylindrical part of a pipe about 30 mm. wide which is rounded off at the bottom and runs out into a pipe union about 10 mm. long and 3 mm. wide).

For the recipitant bath warm diluted sulfuric acid is used in the .known manner to which, essentially for increasing the sheen and softness, there are added one or more of the substances known for this purpose (glucose, sulfates, oxy-a'cid, poly-atomic alcohols, etc.). The same admixtures can be made to the viscose itself.

The minimum acid concentration of the spinning bath then measured approximately rename at a fully suflicient spinning length of 10-30 cm.

With 7 de With 4' de- With 2 defi as a as as 4 r. 4 r. pr. liter? liter? ml.

E sample I l A viscose is used in the manufacture of which the alkali cellulose divided up into small boxesihas been allowed to stand uncovered only a short time after leaving the grinding works or mills in order to acquire a uniform room temperature, the sulfidizing having been carried out up to good solubility under the usual avoidance of increase in temperature and in which the solution was also effected at once Without increase of above tables are preferably considerably exceeded, and, namely, all the more all the higher the consistency of the viscose with 'a'n'equal percentage of cellulose.

The necessary higher acidity is'thus shown to be quite convenient, inasmuch, as although the decomposing reaction steadily becomes it allows the spinning stretch to be maintalned as before within the limits of 10 to 30 cm.

The use even of relatively highly concentrated acid with such immature and consequently thick viscose is free from objection,

shorter,

I as the xanthogenate therein first sa'ponifies but very little and consequently butvery little sulfur of sodium is present so that, on decomposing the viscose, no evolution Worthy of mention of sulfureted hydrogen takes place, so that it is not necessary to take any steps to render this gas innocuous. The threads arising from the spinning bath are generall covered with a lar er quantity of sulfur t an in Example I. oreover after the washings the same can be easily and,

harmlessly dissolved out.

It seems in a highly desirable manner to insure that no all-too-rapid, and consequently under certain conditions, prejudicial, decomposition of the viscose threads takes place.

What I claim is The process of producing viscose threads of any desired fineness from raw viscose of various consistencies, which comprises forcing the viscose throu h suitable openings into an acid precipitating bath, the concentration of which is increased proportionately to the increase in the fineness of the thread desired to be produced, the increase inth consistency of the viscose used, and the increase in the size of the openings through which the viscose is forced.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

EMILE BRONNERT.

Witnesses:

L. Rum SALIs, N. H. MUMBERGEB. 

